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Asymmetric airfoils are commonly used in horizontal axis wind turbines, while symmetrical airfoils are currently the focal point of the researches for most vertical axis wind turbines' airfoils studies. The purpose of this paper is to research the influence of asymmetric airfoils on the aerodynamic performance of vertical axis wind turbines. The influence of asymmetric airfoils on the aerodynamic characteristics of vertical axis wind turbines is investigated by numerical simulation method. The symmetric airfoils are chosen as NACA0021, while the asymmetric airfoils are chosen as DU97-W-300. Single-blade, 3-blade, different tip speed ratios, and three wind speeds (7, 8, 9 m/s) are set as the parameters. The wind turbine with symmetric airfoils performed better aerodynamically at high tip speed ratios, whereas the wind turbine with asymmetric airfoils performs well at low tip speed ratios. The wind turbine with asymmetric airfoils has outstanding start ability at low wind speeds. [ABSTRACT FROM AUTHOR]

This paper introduces a numerical approach for the fractional-order Rössler chaotic systems and gives error analysis. The effectiveness of the present method is determined by comparing the numerical results of the high-precision difference scheme and predictor-correctors scheme. Some complex dynamical behaviors for the fractional-order Rössler chaotic systems are shown. [ABSTRACT FROM AUTHOR]

Stratospheric airships require a lightweight envelope to contain lighter-than-air buoyancy gas, making the lightweight design and pressure-bearing performance of the envelope structure a key research issue. The stress state at different cross-sectional positions of the airship envelope structure is different, resulting in a low utilization rate of the overall material performance of the envelope structure. This paper proposes a design scheme for reinforcing envelope structures with sliding reinforcing cable to improve the bearing capacity of the composite fabric structure while reducing its weight, ultimately achieving the optimal strength-to-weight ratio. Two types of composite fabric structures (A-airship and B-airship) were subjected to inflatable burst tests, and the strain changes in the envelope gores were analyzed by digital image correlation. Through re-assembly of the broken composite fabric pieces and analysis of their tear textures, crack origination positions, failure causes, and the stress behavior and state at the failure position were identified. An envelope structural model with consideration of the cutting pattern effect was established, allowing the stress distribution of the envelope to be analyzed and the damage positions to be more accurately predicted. Based on the analysis of the ultimate pressure-bearing performance of an airship envelope structure, a novel idea of incorporating coupled tensile-shear stress into the strength criterion was proposed. Through the data in the study and existing references, it is verified that the strength criterion can accurately predict the ultimate pressure-bearing performance of the envelope structure. [ABSTRACT FROM AUTHOR]

This paper proposes an assembled X-shaped flexural steel damper. Welding is waived for the novel damper. As the kernel element of the damper, the X-shaped flexural steel plates have the advantages of ease of installation and replacement if necessary. In the analytical part, the effective height of the flexural steel plate was suggested, and then, the yield displacement, yield load and initial stiffness of the damper were derived. The proof-of-concept cyclic loading test was conducted using one reduced-scale specimen within a four-bar linkage experimental setup. The hysteretic performance indexes, including strength, stiffness and energy dissipation, were quantified. The high-fidelity finite element (FE) models were established by ABAQUS. The parametric study was further conducted based on the verified FE model. The considered parameters were the height and thickness of the steel plates. The testing results indicate that the proposed damper has plump hysteretic curve with good energy dissipation capacity and excellent ductility, although slight slip behavior can be found due to the gap caused by the assembling process. The results obtained from analytical method and numerical model are in good agreement with the experimental data. The results of parametric analysis show that the numerical results well agree with analytical predictions, indicating the numerical model can reflect the mechanical behavior of AXSFD. A benchmark frame building was selected to demonstrate the seismic control efficacy of the damper. The nonlinear time history analysis results indicate that the damper reduced both peak and residual interstory drift ratios for the protected structure. [ABSTRACT FROM AUTHOR]

Aiming at the cooperative control problem of multi-agent system, the fixed-time containment control of general second-order multi-agent system under mismatched disturbances is studied. Firstly, the problem of multi-agent system fixed-time containment control in ideal state is analyzed, and a distributed control protocol based on variable structure control is proposed. Then, a nonlinear fixed-time disturbance observer is designed, aiming at the mismatched disturbance, and a fixed-time control protocol based on the nonlinear disturbance observer is proposed. Finally, the effectiveness of the proposed control protocol under switching topology and multi-source disturbance is verified by numerical simulation. [ABSTRACT FROM AUTHOR]

Servo dynamic stiffness is a pivotal index in characterizing the rejecting performance for the exogenous periodic disturbances of the repetitive learning control system. In this paper, the mathematical modeling of the servo dynamic stiffness for the well-designed repetitive learning control system with multiple-periodic signals is studied by the frequency analysis method. To analysis the complex form of the servo dynamic stiffness, the magnitudes of the direct (real part) and quadrature (imaginary part) servo dynamic stiffness at harmonics of the disturbance are discussed based on the parameters of the repetitive learning controller. An illustrated example of the two linear servomotors with the mechanical coupling is given in this study. Computer simulation are presented to illustrate the effect of the proposed measurement method of the servo dynamic stiffness for the multiple-periodic repetitive learning control system. The proposed servo dynamic stiffness modeling can be used to accurate design the parameters of the repetitive learning control system, such that the batter control performance of the repetitive learning control system at most of the harmonics of the multi-periodic input signal can be achieved. [ABSTRACT FROM AUTHOR]

Addressing the challenge of rehearsing large-scale equipment assembly, particularly for oversized components like wind turbine towers, hubs, nacelles, and blades, which often face quality issues such as substandard workmanship and wide tolerances during on-site assembly, a system has been developed for simulating wind turbine assembly. This system enables digital wind turbine assembly by creating virtual and production process models and employing intelligent database analysis. It resolves the problem of the absence of pre-production for large-scale equipment, meets the batch production needs of the wind turbine manufacturing industry, enhances the safety of wind turbine operations, improves operator assembly skills, and boosts production efficiency. This platform has already been implemented in the wind turbine manufacturing industry, yielding significant economic benefits. [ABSTRACT FROM AUTHOR]

Objective: Creation of a novel 3D-printed physical cochlear model that demonstrated the feasibility of creating the model, and impact of a Graphical User Interface (GUI) system on training insertion metrics. Study Design: Feasibility study with a pilot prospective data collection. Setting: Tertiary academic center. Methods: The study was IRB exempt. Five resident trainees (PGY1-PGY5) practiced electrode insertions in cadaveric temporal bones before using the simulator. Nine students were educated on how to hold the electrodes and position them, and then allowed to use the simulator. All trainees were instructed that slower insertions were favorable. One cochlear implant (CI) surgeon used the simulator. The GUI captured the real video feed, but also provided distance, trajectory, and velocity measurements. The program is designed to plot the real-time depth of insertion and speed of insertion of the electrode; the user is also provided real-time occurrence of any kinks and back-outs. Results: A total of 14 trainees and 1 CI surgeon inserted the electrode at least 5 times without the use of the GUI (before) and then at least 5 times with the use of the GUI (after). Average Speed before and after (100.84 and 53.23 mm/s); Average minimum speed before and after (59.34 and 9.65 mm/s); and Average maximum speed before and after (416 and 285.81 mm/s). Statistically significant improvements were noted in all the measured speeds of insertion (P <.001). The other variables improved but not to a statistical significance. Conclusions: Real-time training using the 3D-printed model and GUI for cochlear implantation can help improve surgical resident training and comfort levels with electrode insertion for surgical trainees. The advantage of this model is that surgeons/trainees can use it as many times as they like, as the whole set-up is easy, economical, and reusable. The real time graphical user interface enhances training and retention of the practiced skills. [ABSTRACT FROM AUTHOR]

Background: Restoring hip anatomy during total hip arthroplasty (THA) is the gold standard. The general goal is for hips to be symmetrical in terms of height. This study aimed to analyse the effect of simulating hip length (HL) equalisation on leg-length difference (LLD) before and after THA with a computerised plan. Methods: 141 consecutive patients were enrolled following THA. Outcomes of interest were preoperative hip-length difference (HLD) and LLD as determined on CT and final LLD as determined by simulating HL equalisation. We divided patients into 3 groups: no LLD, LLD >5 mm and LLD ⩾10 mm. Results: The rate of preoperative LLD >5 mm and LLD ⩾10 mm was 37.5% and 14.8%, respectively. HL equalisation did not change LLD distribution in the overall cohort. Among patients with smaller preoperative HLs and LLDs, HL equalisation changed the rate of LLD >5 mm from 100% (n = 24) to 41.7% (n = 10) (p < 0.0001) and of LLD ⩾10 mm from 100% (n = 12) to 16.7% (n = 2) (p < 0.0001). Among patients with no preoperative LLD, HL equalisation changed the rate of LLD ⩽5 mm from 100% (n = 64) to 59.3% (n = 38) (p < 0.0001) and of LLD<10 mm from 100% (n = 76) to 89.5% (n = 68) (p = 0.006). Conclusions: Restoring biomechanical hip anatomy by HL equalisation may not be the correct goal for all patients. In patients with no LLD and shorter HLs, equalisation could result in LLD >5 mm in 40% of patients and LLD >10 mm in 10%, demonstrating the necessity to further analyse individuals and propose a personalised stem position. [ABSTRACT FROM AUTHOR]

Objective: To identify specific areas for improvement in cleft lip repair teaching. Design: Secondary analysis of prospectively-collected, blinded data. Setting: Three residency programs rotating at a single academic children's hospital. Participants: Plastic surgery residents, and craniofacial/pediatric plastic surgery fellows. Main Outcome Measures: Mean scores for each skill in an 18-item Unilateral Cleft Lip Repair competency assessment tool (UCLR) (1–3 scale for each item) were rank ordered. Correlation between level of training (PGY) and performance on steps of the procedure was examined using Pearson R. Results: Simulation participants (n = 26) scored highest on skills in the "Marking" subscale (2.38–2.63 mean score). Procedural steps that scored lowest were: closing the nasal floor (2.00), repairing oral mucosa (2.15) and avoiding over/under-dissection (2.19). Interestingly, none of these skills correlated with PGY, suggesting they do not improve with training. Conclusions: These results suggest that marking cleft lip repair is taught well in our current teaching environment, while steps like closing the nasal floor and repairing the oral mucosa are taught less well. Improved teaching of these steps could be achieved with deliberate instruction, video, digital simulation, and high fidelity simulation. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tube (CFST) members have been widely used in skyscrapers and long-span bridges. Non-uniformly distributed hydration heat during curing, inadequate compaction during construction and unavoidable shrinkage and creep of mass concrete in service most likely lead to interface debonding defects between concrete core and steel tube, which has been a common concern. The development of effective non-destructive inspection methods for interface bonding condition of existing CFST members is critical. In this study, an interface debonding defect detection method based on electromechanical impedance (EMI) measurement using surface-mounted piezoelectric-lead-zirconate-titanate (PZT) sensors is proposed at first. Then, experimental study on the feasibility of the proposed approach is carried out with scaled CFST specimens with artificially mimicked interface debonding defects. EMI of surface-mounted PZT sensors at different frequency bands are measured and compared to verify the detectability of the proposed approach for the mimicked interface debonding defects. Thirdly, a multi-physics CFST-PZT coupling finite element model (FEM) with interface debonding defects is established, and EMI of surface-mounted PZT sensors at different locations is simulated. The influence of interface debonding defects on EMI measurements is illustrated. Finally, a blind inspection on the interface bonding condition of selected CFST columns in an existing skyscraper in service using the proposed approach is carried out. Both bonding and debonding defect in the tested CFST columns are detected correctly and validated with drilling hole observation. Experimental, numerical and engineering application results show the proposed approach is effective for interface debonding detection of CFST members and sensitive to minor debonding defect of 0.3 mm in CFST members. [ABSTRACT FROM AUTHOR]

Introduction: Teaching inhaler techniques to nursing students is crucial. Objective: This study aimed to investigate the effect of simulation-based education on patient training correct inhaler technique in nursing students. Methods: This is a single-blind, randomized controlled trial in which nursing students are randomly allocated into two groups of control (n = 41) and intervention (n = 40). The students' mean score of correct inhaler technique was measured before and one week after intervention, using checklists of inhaler techniques. Results: The mean score of control group was significantly lower than the intervention group (p <.001). The results also revealed that there was no significant difference in students' level of confidence regarding the ability to educate patients on inhaler techniques before the intervention, while all students were shown to have higher levels of confidence in this term after the intervention. Conclusions: Simulation is an effective way to train nursing students in the correct inhaler techniques. [ABSTRACT FROM AUTHOR]

Purpose: Mental health providers are well-positioned to engage in suicide prevention efforts, yet implementation depends on skill acquisition and providers often report feeling underprepared. This pilot study explored the acceptability, feasibility, and preliminary effectiveness of three suicide prevention-focused simulations with virtual clients. Method: Students (n = 22) were recruited from a Master of Social Work program, completed pre- and post-test surveys, and engaged with three simulated trainings: (1) suicide risk assessment, (2) safety planning, and (3) motivating a client to treatment. Results: Simulations were reported to be acceptable and feasible, with strong student desire and need for greater suicide prevention training. We observed significant improvements over time in clinical skills via simulated training scores and perceptions of clinical preparedness. Discussion: Preliminary findings indicate simulated training with virtual clients is promising and suggest the three suicide prevention simulations may be useful, scalable, and effective in social work training programs and beyond. [ABSTRACT FROM AUTHOR]

Multiple imputation (MI) is one of the recommended techniques for handling missing data in ordinal factor analysis models. However, methods for computing MI-based fit indices under ordinal factor analysis models have yet to be developed. In this short note, we introduced the methods of using the standardized root mean squared residual (SRMR) and the root mean square error of approximation (RMSEA) to assess the fit of ordinal factor analysis models with multiply imputed data. Specifically, we described the procedure for computing the MI-based sample estimates and constructing the confidence intervals. Simulation results showed that the proposed methods could yield sufficiently accurate point and interval estimates for both SRMR and RMSEA, especially in conditions with larger sample sizes, less missing data, more response categories, and higher degrees of misfit. Based on the findings, implications and recommendations were discussed. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a framework for 3D subject-specific computational models capable of simulating velopharyngeal biomechanics for anatomic changes that occur following pharyngoplasty and to gain insight into biomechanical factors that may lead to different speech/surgical outcomes. Patient-specific models for two, matched participants with differing speech/surgical outcomes were developed: one with a successful pharyngoplasty outcome and one with a failed pharyngoplasty outcome. Surgical scenarios were simulated to model pharyngoplasty location, identify LVP muscle biomechanics, and identify an optimal pharyngoplasty location for each participant. These simulations illustrate the potential for optimizing pharyngoplasties based on patient-specific geometry. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of high-speed train aerodynamic noise analysis and provide a feasible method for aerodynamic noise prediction, the aerodynamic noise and its influencing factors are analyzed from the perspective of the total energy (sound power) radiated to the far field per unit time by the aerodynamic fundamental noise sources (monopole, dipole and quadrupole sources). A full-scale and a 1:8 scale-down computational fluid dynamics model of a high-speed train are established. The far-field sound pressure level at several receivers and velocities is calculated by using the transient large eddy simulation and the FW-H equation. The numerical simulation results are used to predict the aerodynamic noise under specified working conditions. The research work can achieve the prediction of aerodynamic noise at other velocities using noise data at known velocities on the same noise source case, as well as the prediction of aerodynamic noise of full-scale model using data of scale-down model, and is applicable to either bogies as local noise sources or the complete vehicle as a noise source. The maximum error between the prediction and simulation result is 0.33 dBA under various working conditions, which meets the engineering calculation requirements. [ABSTRACT FROM AUTHOR]